Currently the contraceptive implant the NHS provides lasts three years but if a woman wishes to remove it before then, she must attend a clinic.

The creators believe it will be more convenient and if it passes safety tests, it could be on the market as early as 2018. They said it would be “competitively priced”.

Pre-clinical testing of the implant, developed by start-up MicroCHIPS in Massachusetts, will begin next year.

The idea for the chip originated two years ago. During a visit to Massachusetts Institute of Technology’s (MIT) lab, Gates and his colleagues asked Robert Langer, professor at MIT, whether it was possible to create birth control that a woman could turn off and on.

MIT said the implant would have to be encrypted to protect wireless data flow and keep it secure.

The chip’s size is 20mm x 20mm x 7mm and reservoirs of the hormone are stored on a 1.5cm-wide microchip within the device.

The implant’s daily dose works by a small electric charge melting an ultra-thin seal around the hormone. This would then release a 30 microgram dose into the body.

The co-creator of the chip, Dr Robert Farra, said that the control would have to be close enough for skin contact.